It has been well known for a number of years to convert heat to electricity through the use of thermionic converters wherein an electron emitter is heated to a sufficiently high temperature so that it emits electrons into the surrounding space where they are received by a juxtaposed electron collector. The electron collector is maintained at a substantially lower temperature than the emitter, and a very low pressure gas, such as cesium vapor, is present in the uniform annular space or gap between the emitter or collector. To increase the overall voltage, a plurality of such cells are appropriately interconnected, i.e. collector of one cell to emitter of the next adjacent cell; an electrical circuit is then completed by connecting an external load to terminals provided on the exterior of the converter.
An early version of such a multiple cell thermionic converter is shown in U.S. Pat. No. 3,702,408 which illustrates a multiple cell thermionic converter wherein a plurality of diodes are stacked on a central heat pipe in a series-connected network of cells within a chamber that contains cesium vapor. The individual cells are interconnected by flexible leads 53 made of molybdenum which contain spirally-oriented slots that allow the cesium vapor to reach the gaps between each of the juxtaposed emitter-collector pairs.
Although constructions made in accordance with such design may have been satisfactory for emitters operating at a temperature of about 1700 K, the search has continued for improved electrical connectors particularly for use in thermionic converters that will operate at temperatures in the vicinity of 2000 K, wherein the difference in elongation between the collectors and the emitters can place substantial demands upon designers to accommodate stresses that will be inherently created.